SU873025A1 - Vibrational density meter - Google Patents

Description

(54) VIBRATION DENSITY

one

The invention relates to a measurement technique and can be used to measure the density of gases, in particular to measure the density of natural gas in gas pipelines and underground gas storage facilities.

Vibration densitometers are known, which contain a metal membrane or blade 1 as a sensitive element that vibrates in a standard and controlled medium of a sensitive element.

However, the sensitivity and, consequently, the accuracy of these densitometers is limited by the rigidity and high inertia of the metal membrane or blade.

A vibrating densitometer is also known, which contains a metal band oscillating in a controlled environment and in vacuum as a sensitive element, a chamber for introducing a controlled medium, an excitation system for creating transverse vibrations of the tape and means for measuring the deviation of the frequency of vibration of the tape in the absence and presence of a controlled medium.

The lack of this densitometer is a low measurement accuracy due to the large inertia of the metal tape, rough manual tuning of the resonance frequency, and the presence of an elastic system that causes a spontaneous change in the tension of the tape during operation 2.

The purpose of the invention is to increase the accuracy of measurements.

This goal is achieved by the fact that in a 10 vibration densitometer containing a probe installed in a controlled gas, a vibration-sensitive element housed in a probe, an excitation system of a vibration-sensitive element, a light source, a light receiver made in 15 form of a photoelectric converter and a measuring circuit, the vibration-sensitive element is designed as an optical fiber filter connected by an optical fiber cable with a light source, the free end of the optical fiber filter being set phenomenon opposite light receiver, and at the free end of the fiber optic secured electret filter.

FIG. 1 shows a functional diagram of the device; in fig. 2 shows the construction of the probe of the device proposed, section.

The device contains a source of light 1, the probe 2 and the measuring circuit 3.

Probe 2 (Fig. 2) includes an optical fiber cable 4 terminating in a base 5 with an optical fiber filter 6, at its free end an electret plate 7 is attached as an end load, as well as an adjustment element 8. The plates 9 of the excitation system are located on the top and bottom of the optical fiber filter, and a photoelectric converter 10 is mounted on the front part of the free end of the filter, which is attached to the inner wall of the protective housing 11, which is sealed from the top by a lid 12, and below there is a grid 13 .

Measuring circuit 3 (Fig. 1) includes a generator 15 with a smoothly varying excitation frequency, a frequency-code converter 16, a frequency key 17, an arithmetic unit 18, and a display unit 19.

The device works as follows.

The signal from the generator 15 enters the plates 9 of the excitation system, and the signal frequency varies from the lower resonance frequency (n, corresponding to the maximum density of the medium monitored, to the upper resonance frequency fj, corresponding to the minimum density of the medium monitored. In the absence of resonance, the unmodulated the luminous flux and the frequency signal at its output are absent. If the excitation frequency coincides with its own resonant frequency Gc.filter, at the input f A modulated luminous flux with a frequency cs (at a certain gas density) appears from the electronic converter. From the output of the photoelectric converter, an electrical signal enters the frequency-code converter 16 and the frequency switch 17, which resets only at the output of a resonant photoelectric converter signal and fixes the frequency

generator 15. From the output of the frequency converter code 16, the code of the resonance frequency enters the arithmetic unit 18, which solves a certain functional relationship between the density of the controlled medium and the frequency of the filter in vacuum and the controlled medium. The result of the processing is displayed on the display unit 19. At the end of the measurement cycle, the arithmetic unit generates a measurement end pulse, which enters the generator 15 and at the arrival of which a signal with frequency I appears on the plates 9. The entire measurement process is automatically repeated. The use of the proposed device provides an increase in the accuracy of density measurement through the use of a sensitive element having a small one. inertia, probe compactness due to the use of optical elements, simplicity of secondary equipment.

Claims (2)

1. Vibratory density meter containing installed in controlled gas probe, vibration-sensitive element, placed in the probe, excitation system of the vibration-sensitive element, light source, light receiver, made in the form of photoelectric converter and measuring circuit, characterized in that that, in order to improve the measurement accuracy, the vibration-sensitive element is designed in the form of an optical fiber filter connected by an optical fiber cable with a light source, with the free end of the optical fiber filter installed opposite the light receiver. 2. A densitometer according to Claim 1, characterized in that an electret is attached to the free end of the optical fiber filter. Sources of information taken into account in the examination 1. The patent of Germany No. 2550375, cl. G 01 N 9/34, 1976. 2. The patent of France No. 2.180.233, cl. G 01 N 9/00, 1976 (prototype).